import sys
from collections import defaultdict
readline = sys.stdin.buffer.readline
#sys.setrecursionlimit(10**8)


def geta(fn=lambda s: s.decode()):
    return map(fn, readline().split())


def gete(fn=lambda s: s.decode()):
    return fn(readline().rstrip())


def main():
    x = gete(int)

    print('Yes' if x >= 30 else 'No')


if __name__ == "__main__":
    main() import sys sys from collections import defaultdict readline = sys.stdin.buffer.readline readline sys.stdin.buffer.readline sys.stdin.buffer sys.stdin sys stdin buffer readline def geta(fn=lambda s: s.decode()):
    return map(fn, readline().split()) geta return map(fn, readline().split()) map(fn, readline().split()) map fn readline().split() ().split () readline split fn=lambda s: s.decode() fn lambda s: s.decode() s.decode() s.decode s decode s def gete(fn=lambda s: s.decode()):
    return fn(readline().rstrip()) gete return fn(readline().rstrip()) fn(readline().rstrip()) fn readline().rstrip() ().rstrip () readline rstrip fn=lambda s: s.decode() fn lambda s: s.decode() s.decode() s.decode s decode s def main():
    x = gete(int)

    print('Yes' if x >= 30 else 'No') main x = gete(int) x gete(int) gete int print('Yes' if x >= 30 else 'No') print 'Yes' if x >= 30 else 'No' x >= 30 x 30 'Yes' 'No' if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def geta(fn=lambda s: s.decode()):
    return map(fn, readline().split()) def geta(fn=lambda s: s.decode()):
    return map(fn, readline().split()) geta readline = sys.stdin.buffer.readline sys.stdin.buffer.readline readline def main():
    x = gete(int)

    print('Yes' if x >= 30 else 'No') def main():
    x = gete(int)

    print('Yes' if x >= 30 else 'No') main def gete(fn=lambda s: s.decode()):
    return fn(readline().rstrip()) def gete(fn=lambda s: s.decode()):
    return fn(readline().rstrip()) gete
import sys
from collections import defaultdict
readline = sys.stdin.buffer.readline
#sys.setrecursionlimit(10**8)


def geta(fn=lambda s: s.decode()):
    return map(fn, readline().split())


def gete(fn=lambda s: s.decode()):
    return fn(readline().rstrip())


def main():
    x = gete(int)

    print('Yes' if x >= 30 else 'No')


if __name__ == "__main__":
    main()